As is the case for all medical illnesses, diagnosis rests upon a careful history and physical examination. The history, as it pertains to food-induced allergic reactions, must focus upon the symptoms elicited, the timing of the symptoms in relation to food ingestion, and reproducibility of reactions. Acute reactions to isolated ingestions should be differentiated from chronic disease related to food. Dietary details are key and a symptom diary may be helpful. The physical examination focuses on the exclusion of non-allergic causes of food-induced symptoms. The physician should be able to conclude the history and physical examination with an idea of whether an allergy or food intolerance is on the differential diagnosis and whether IgE or non-IgE mediated mechanisms are playing a role.